title: Effects of low-dose dopamine on renal and systemic hemodynamics during incremental norepinephrine infusion in healthy volunteers.
abstract: OBJECTIVE
  To assess the effects of low-dose dopamine on norepinephrine-induced renal and systemic vasoconstriction in normotensive healthy subjects.
  
  
  METHODS
  On separate days, either a low-dose dopamine (4 microg/kg/min) or a placebo (5% glucose) infusion was added in a single, blinded, randomized order to incremental norepinephrine infusions of 40, 80, and 150 ng/kg/min over a 60-min period each.
  
  
  METHODS
  Outpatient clinic of a university-affiliated hospital.
  
  
  METHODS
  Normotensive healthy volunteers.
  
  
  METHODS
  Infusions of norepinephrine and dopamine.
  
  
  RESULTS
  Blood pressure and heart rate were measured with a semiautomated device, and glomerular filtration rate and effective renal plasma flow were determined with constant infusions of 125I-iothalamate and 131I-hippurate, respectively. Norepinephrine alone progressively increased mean arterial pressure to pressor levels, whereas this effect was attenuated by the addition of dopamine (p < .05 vs. norepinephrine alone). Glomerular filtration rate increased during lower norepinephrine doses and did not decrease at the highest norepinephrine dose. Addition of dopamine further increased glomerular filtration rate. Effective renal plasma flow decreased with each norepinephrine alone infusion step, but this decrease was completely prevented by concomitant dopamine infusion (p < .01 vs. norepinephrine). Sodium excretion tended to decrease with norepinephrine, but increased two- to three-fold after addition of dopamine (p < .01 vs. norepinephrine alone).
  
  
  CONCLUSIONS
  In healthy man, norepinephrine causes a large decrease in renal plasma flow but not in glomerular filtration rate. Concomitant dopamine administration prevents this decrease in renal plasma flow, increases sodium excretion, and also attenuates the norepinephrine-induced systemic blood pressure increase. These findings warrant further clinical evaluation of the effect of concomitant low-dose dopamine and norepinephrine administration in critically ill patients.
authors.affiliation: Department of Internal Medicine, University Hospital Groningen, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Hoogenberg
authors.forename: A J
authors.initials: AJ
authors.lastname: Smit
authors.forename: A R
authors.initials: AR
authors.lastname: Girbes
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage* / Q000097:blood; D000328:Adult; D004298:Dopamine / Q000008:administration & dosage* / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007262:Infusions, Intravenous; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage* / Q000097:blood; D012016:Reference Values; D017596:Renal Plasma Flow, Effective / Q000187:drug effects; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000008:administration & dosage* / Q000097:blood
chemical_list: D000317:Adrenergic alpha-Antagonists; D014662:Vasoconstrictor Agents; D004298:Dopamine; D009638:Norepinephrine